package com.hmdp.utils;

import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.entity.Shop;
import lombok.extern.slf4j.Slf4j;

import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.hmdp.utils.RedisConstants.LOCK_SHOP_KEY;

@Slf4j
@Component
public class CacheClient {

    private StringRedisTemplate stringRedisTemplate;

    public CacheClient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    public void set(String key, Object value, Long time, TimeUnit unit) {
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value), time, unit);
    }

    public void setWithLogicExpire(String key, Object value, Long time, TimeUnit unit) {
        RedisData redisData = new RedisData();
        redisData.setData(value);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(redisData));
    }

    /**
     * 防止缓存穿透的query
     * @param keyPrefix
     * @param id
     * @param type
     * @param dbFallback
     * @param time
     * @param unit
     * @return
     * @param <R>
     * @param <ID>
     */
    public <R, ID> R queryWithPassThrough(String keyPrefix, ID id, Class<R> type, Function<ID, R> dbFallback, Long time, TimeUnit unit) {
        String key = keyPrefix + id;
        String json = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isNotBlank(json)) {
            return JSONUtil.toBean(json, type);
        }

        if (json != null) {
            return null;
        }

        R r = dbFallback.apply(id);
        if (r == null) {
            stringRedisTemplate.opsForValue().set(key, "", RedisConstants.CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        this.set(key, r, time, unit);

        return r;
    }

    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    public <R,  ID> R queryWithLogicExpire(String keyPrefix, ID id, Class<R> type, Function<ID, R> dbFallback, Long time, TimeUnit unit) {
        String key = RedisConstants.CACHE_SHOP_KEY + id;
        String json = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isBlank(json)) {
            return null;
        }

        RedisData redisData = JSONUtil.toBean(json, RedisData.class);
        JSONObject data = (JSONObject) redisData.getData();
        R r = JSONUtil.toBean(data, type);
        if (redisData.getExpireTime().isAfter(LocalDateTime.now())) {
            return r;
        }
        String lockKey = LOCK_SHOP_KEY + id;
        boolean getLock = tryLock(lockKey);
        if (getLock) {
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    // 查数据库
                    R r1 = dbFallback.apply(id);
                    // 写入缓存
                    this.setWithLogicExpire(key, r1, time, unit);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    unLock(lockKey);
                }
            });
        }

        return r;
    }

    public boolean tryLock(String key) {
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return Boolean.TRUE.equals(flag);
    }

    public void unLock(String key) {
        stringRedisTemplate.delete(key);
    }


}
